Circuit breaker



Oct. 20, 1953 G, J, FREESE 2,656,436

' CIRCUIT BREAKER Filed April 29, 1949 Fig'.4. 55

off EFX se, onv

WITNESSES: INVENTOR Gerold J. Freese.

Patented Oct. 20, 1953 UNITED STATES PATENT OFFICE CIRCUIT BREAKER Gerald .J .Freese Beaver, Pa, assigner to Westinghouse Electric Corporation, -East Pittsburgh, Pa., a corporation'of Pennsylvania Applioation April'?. 1949, .Seriallo. 99,463

(Cl- 200e-'116) k1'7 Claims. 1

The invention relates to circuit breakers, and more particularly to manually and automatically operable low voltage circuit breakers for controlling lighting and other moderate power .electric circuits.

An object of the invention is to provide an improved circuit breaker having ka minimum .of parts, that is compactI light in weight and reliable in operation, .and inexpensive to manufacf ture.

Another object of theinvention is to provide a circuit breaker embodying an operatingmech.- anism having asmall number of parts which ,are readily assembled and disassembled.

Another object of the invention is to` provide a circuit; breaker embodying animprovod thermal trip means for `effecting ,automatic operation of the breaker.

The novel features 4that are .considered characteristic 4of the invention are kset Aforth in particular in the appended claims. The invention itself, however, both as to structure andoperation, together with additional objects and ladvantages Will be best understood from the Ifollowing detailed description thereof ywhen read inconjunc.- tion with the .accompanying drawing.

In said drawing:

Figure l isa side elevational view of a .Circuit breaker, with the coverplate removed, the cire cuit breaker in .the closed position, embodying the principles of .the invention. f

Fig. 2 is a vertical sectional view ,taken ron line II-IIof Fig l,

Fig. 3 is `a side elevational view similar to Fig.

1 but showing the circutbreaker in they manually Y opened position.

Fig. 4 Ais a side elevational view of .the circuit breaker showing the ,parts .in the tripped open position, and

Fie. 5 is a .fragmentary elevationa1.vievwshovvF ing a modification .of the invention.

yReferring to Figs. l-l of thedraw-ing. the .oirP cuit breaker comprises in general a twofpartseparable enclosure of molded'insulating material including a housingmember 4I i and abovezrplate I3 therefor, a stationary Contact |,5,ga .cooperatme movable .Contact l?! carried ibv Aa .resilient switch member I9, an operating,mechanismindicated generally at 2|, a current responsivetrip device indicated generally .at 23 and a pair .of terminals .25.,and 21 y,for connecting `the. breaker in anelectrical circuit.

The resilient Switohmember i9., .at ,its end opposite 'the movi-ng ,contact v IFI is given areVerSe bend vand the formed end :2a9 is -fsecured as'by rivets l3| as shown or by Welding to an Aarm 3,3. The arm 3.3 has. ears .35 ,formed thereon whereby it is pivotally mounted by means .of ,a pin 3l on a `bracket 39 secured to the base portion l of the housing lI l. Between the portion y2S) of the switch member L9 and the arm 3 3 is ,secured the foot 43 .of a current responsive bimetal element t5` ,formed atright anglesto the yfoot ,43 thereof.. The vfree end of the bimetai element ,e5 is connected by means .of a flexible conductor 47 to the terminal .27.. .thus .completing the Circuit through the breaker.

The circuit .through the breaker .extends .from the terminal 25 through the stationary contact I5the movable 4contact .-I l, the switchmeinber I9, the bimetal element .43.7.45 andthe rflexible .conductor ll tothe terminal 2,

The operating mechanism 2i includes en operating lever `t9 pivcted `on a pinl `-mounted in the side wall of .the housing il. The voperating lever Vhas `an ,angular .portion I,5.3 at its Tree end to which is seoured a manualoperatine .handle V5.5 which extends outwardly through an ,opening 5] ,in the housing ,I l. The handle ,5,5 is of molded insulating material and has molded integral therewith yan arcuate closure portion 59 for substantially .Closing the .opening 51 inail positions Qf thehandle..

Mounted for rotation .on the fixed pin 5I is a cam wheel ,6I havnsa plurality or .care portions 63 formed thereon. ,In the iclosed positiv.n of the .breaker one of the oem portions 63 .engages a pin 65 in a formed portion tl' of the switch member I9 to vrestrain the switch member in closed position,

The switch member vI9 lis lbiased open by its inherent resiliency and also by a spring .69 tensioned between the outer end Aof the yoperating lever ,4,9 and Aa pin 'Il on the portion S1 ofthe switch member I. The pin `655 vin ,the .closed position engages the Garn vportieri E3 slightly lO the right of the high .portion thereof and consequently urges the cam Wheel E I .to rotate in a clockwise direction about its pivot 5I, `Clockwise rotation of the Icam Wheel 5I, however, is normally prevented vby .the engagement of a com surface A'L3 -on the adjacent cam .portion with a 4pin 'l5 on one arm 1:1 vof a threefarnied latch member indicated vgenerally at TF9. The `latch member 19 is pivotally mountedon a -pin Si suppor-,ted kin .the side Wall .of the housing Il. The latch 19 iS biased by means .of a spring :82 in unlatchirlg A,direction ,and is normally restrained in latching position .by the engagement of a latch arm @thereof vavith-a .latch Aon the free end 3 of the bimetal element 4t. The third arm 81 of the latch member i9 is for the purpose of effecting manual opening of the contacts and resetting the latch following an automatic operation in a manner to be presently described. The cam wheel 5l is provided with a series of laterally projecting pins 89 which are adapted to be engaged by a resilient catch 9i on the operating lever G9 for the purpose of closing the contacts.

The circuit breaker is opened manually by moving the operating handle 55 and thereby the operating lever 9 in a counterclockwise direction from the on position (Fig. i) to the oi position (Fig. 3). Near the end o the counterclockwise movement the operating lever 49 engages the arm 87 of the latch member' '19 and rotates it slightly in a counterclockwise direction. This movement, acting through the arm 'il of the latch member and the pin 'I5 rotates the cam wheel "i counterclockwise far enough to move the high point of the cam portion 63 overcenter to the right of the pin G5, whereupon the spring tension of the switch member Iii aided by the spring Se causes the pin t5 to act on the cam surface Z3 and rotate the cam wheel Sl further counterclockwise until the pin S5 rests in one of the low points e3 of the cam wheel. This action takes place quickly under the bias of the springs l!) and t9 as soon as the high point of the cam portion S3 passes by the pin e5, with the result that the contacts are opened with a snap action. A clearance opening 95 (Fig. 2) is provided in the switch member le so that the switch member IS does not strike the cam portion S3 in the open position. The parts have now assumed the positions in Which they are shown in Figure 3 with the contacts in the open position.

The circuit breaker is closed by moving the handle 55 clockwise from the off position (Fig. 3) to the on position (Fig. l). During this clockwise movement, the catch 9i on the operating lever 453 engages the adjacent pin 89 on the cam wheel 6I and rotates the latter also in a clockwise direction. During the clockwise rotation of the cam wheel 6i, the cam surface 13 adjacent the pin EE acts on the pin to cam the switch member i9 downward to close the contacts. Just as the high point of the cam portion passes to the left of the pin S5, the cam surface E3 next in clockwise direction from the one which just acted on the pin G5 engages the pin 75 on the latch member l5 and is stopped thereby.

It may be observed that the spring GQ, in addition to assisting in the opening operation, also holds the operating handle :iS- 55 in the on and the oi positions. rhis is due to movement of the spring overcenter across the pivot 5i for the handle when the handle is moved to the on or off positions.

The circuit breaker is tripped open automatically in response to overload currents by operation of the trip device 23. The bimetal element i5 is heated by overload currents nowing therethrough and, when heated a predetermined amount, deilects toward the left (Fig. 1) and releases the latch member '.l. The resilient switch member i9 aided by the spring 59 immediately snaps to the open position. During the opening movement or the switch member 2S, the pin acting on a cam surface 95 on the opposite side of the cam portion (i3 from the cam surface i3, rotates the cam wheel 5l clockwise until the pin is arrested by engagement thereof with the low point 93 between the adjacent cam portions 63. Also during the opening movement oi the Switch member l G the spring 39 moves over to the left of the pivot 5l for the operating lever, whereupon the operating lever 43 is moved in the direction of the oi position. The operating handle is arrested in an intermediate "indicating position by engagement of the operating lever 4t with the arm 8l of the latch member i9 which was moved by its spring 32 to the position shown in Fig. 4 upon its release by the bimetal element.

Before the contacts can be closed following an automatic opening operation, it is necessary to reset and relatch the trip device which is accomplished by moving the handle from the tripped open position (Fig. 4) to the ori position as shown in Fig. 3. During this movement the operating lever 4S acting on the arm 8*; of the latch member le rotates the latter coun clockwise to the Figure 3 position, the latch arm S3 wiping by the latch 85 near the end of the resetting movement. The cam wheel Si does not rotate during the resetting operation since it is held by the spring 59 pressing the pin 55 into the low point 93 between the cam portions 63. During the resetting movement of the operating lever 43, the resilient catch Si wipes by the pin 59 adjacent thereto and snaps back into alignment with the pin in readiness for a closing operation.

Following reengagement of the latch arm 83 with the latch the contacts are closed in the previously described manner by movement of the handle from the od position.(Fig. 3) to the on position (Fig. 1).

An adjusting screw 3'! (Fig. l) is provided to adjustably vary the tripping point of the breaker. The screw 9'! threadedly engages the portion 29 of the switch member, the mounting foot 43 of the bimetal element 45 and the arm 33 adjacent the point where these members are rigidly secured together and adjacent the free end of the arm The rounded head oi the screw 9'? bears against a concave surface of the base portion Gl of the housing Il. An opening is provided in the base portion 4i to admit a tool whereby the screw 9'! may be rotated. Rotation of the screw Sl effects rotation of the arm 33 about the pivot 3l and moves the bimetal element G5 bodily therewith to vary the latch overlap to thereby vary the tripping point of the breaker. Movement of the arm 33 by rotation of the screw 9'." also nexes the resilient switch member I9 to vary the contact pressure.

According to the modification shown in Figure 5, means is provided to compensate the thermally responsive trip device for variations in lambient temperatures. The trip device of the modification is mounted in a housing 98 (only a fragment of which is shown) similar to the housing li shown in Figs. l, 3 and 4. A lever 9S (Fig. 5) is pivoted on a pin IDI which is supported in a bracket ID3 secured to the bottom portion |05 of the housing E8. A switch member ie? has a mounting foot 109 formed thereon which is secured to the lever 99. Also secured to the lever 99 is the mounting foot l il of a bimetal element H3, the mounting feet IDS and IH being rigidly secured to the lever 99 by welding or, as shown. by a rivet H5. rhe free end of the bimetal element is provided with a latch I Il' for cooperation with the latch member 19 and the switch member |01 has a projection H9 carrying a pin 12| for cooperation with the cam wheel 6l (Fig. 1). Secured to the underside of the lever 9 is a temperature responsive, expansible metallic element |23 which is biased'by means of a spring |25 into engagement with an adjusting screw '|21 threadedlyengaging an opening in the base portion |05 of the housing. The spring |25 is compressed between a bracket |23, inserted into and held in place in an angular slot in the base |05, andthe free end of the lever 99.

lRotation oi the screw 21 in a direction to ad- Vance it inwardly will elect upward movement of the lever 99 and thereby increase the overlap of the latch ll'l and increase the contact pressure. Turning the screw |21 in the vopposite direction permits the spring |25 to move the lever 89 downwardly to decrease the overlap of the latch thus varying the tripping timeof the breaker. Backing the screw |21 out also decreases the contact pressure.

The Atemperature responsive element v|23 expands and contracts accordingly as the temperature of the surrounding medium increases and decreases to compensate the tripping bimetal element for changes in ambient temperatures. Upon a rise in ambient temperature the element |23 expands and causes clockwise rotation of the bimetal support lever 99. When the temperature of the surrounding medium decreases, the element |23 contracts permitting the spring 25 to move the lever 99 counterclockwise. In this manner flexing .of the tripping bimetal element I3 in response to changes in temperature of the surrounding air is compensated. Thus, the amount of latch overlap rem-ains constant. The temperature responsive element (|23) only cornpensates for the deliection of the bimetal element due to change inambient temperature.

While the invention has been disclosed in accordance with the provisions oi the patent statutes, it is to be understood that various `changes in the structural details thereof may be made without departing from some of the essential features of the invention.

I claim as my invention:

l. A circuit breaker comprising stationary and movable contact means, a resilient switch member biased open and carrying said movable contact means, a rotatable member having a plurality of radial cam portions thereon, one of said radial cam portions normally engaging said -switch member to maintain said switch member closed against its normal bias, a latch member having a portion engaging another of said radial cam portions to releasably restrain said rotatable member, a trip device operable to release said latch member and permit said vbiased switch member to rotate said rotatable member in one direction to effect automatic opening movement of said switch member, and manual means movable between off and on positions and operable when moved from said off position to said on position to engage and rotate said rotatable member in said one direction to Vcause a. third radial cam portion to engage and cam said switch member to closed position.

2. A circuit breaker comprising stationary and movable contact means, a switch member carrying said movable contact and biased in opening direction, a rotatable member having a, plurality of radially extending portions thereon, one of said radial portions normally engaging and restraining said switch member in closed position against its normal bias, restraining means engaging another of said radial portions to releasably restrain said rotatable member, `and a current responsive trip device operable in response to overload currents "to release `said restraining' means lto'permit said biased lswitch member'to rotate said rotatable member and effect Aautomatic opening movement of said switch member.

.3. A circuit breaker comprising stationary and movable contact means, a switch member carrying said movable contact and biased 'in opening direction, a rotatable member having a r)plurality of radial cam portions thereon, one of said radial cam portions normally restraining said switch member in closed position against its bias, restraining means engaging 'another of said radial cam portions toreleasably restrain said rotatable member, a current responsive trip device operable in response to overload currents to release said 'restraining means to permit the bias of said switch member to rotate .said rotatable member andeffect automatic opening movement of 'said switch member, and -manual means operable to engage and rotate 4said rotatable member in said one direction to cause one of said radial .oamfportions to engage and ,move said switch member to closed position.

ll. A circuit breaker comprising a switch member movable to open and close the circuit, biasing means biasing said switch member in opening direction, a rotatable cam member having a plurality of radially extending cam portions thereon, one of said'cam portions normally holding said switch member in closed position, ,a pivot for said cam member, restraining means cooperating with another of said radio cam portions to releasably .restrain saidcam memberin position to hold said switch member closed, trip means restraining .said restraining 4means operable to release said restraining means to effect automatic opening movement of said switch member, and manual means pivoted on said `pivot and movabie in one direction to engage and actuate said restraining means to cause said lrestraining means to rotate said cam member in one direction to permit said biasing means to move said switch member in opening direction, said manual means being movable in another ldirection to engage and rotate said cam member in another direction to cause said cam member to move said switch member tc closed position.

5. A circuit breaker comprising separable contacts, a switch member movable to open andclose y said contacts, a pivoted lever supporting said switch member, biasing means biasing said switch member in opening direction, a rotatable cam member normally engaging and holding said switch member in closed position, said biasing means also biasing said cam member for rotation in one direction to permit .opening vmovement of said switch member, a releasable inember normally restraining said rotatable cam member against rotation, trip means mounted on said pivoted lever for restraining said releasable member, said trip means being operable to release said releasable member and effect automatic opening movement of said switch meinber, and adjusting means for adjusting `said pivoted lever to thereby vary the tripping time of the breaker.

6. A circuit breaker comprising separable contacts, a switch member movable to open and close said contacts, a pivoted lever supporting said switch member, biasing means biasing said switch member in opening direction, a rotatable cam member normally engaging and holding said switchinember in closed position, said-biasing means also biasing said cam member for rotation in lone direction to-permit `openingrnovement of said switch member, a releasable member normally restraining said rotatable cam member against rotation, trip means mounted on said pivoted lever for restraining said releasable member, said trip means being operable to release said releasable member and eiiect automatic opening movement of said switch member, adjusting means for adjusting said pivoted lever to thereby vary the tripping time of the breaker, and a thermally responsive element disposed between said pivoted lever and said adjusting means for compensating said trip means for changes in ambient temperatures.

7. A circuit breaker comprising relatively movable contact means, a resilient switch member movable to open and close said contact means, operatingmeans operable to eect automatic opening movement of said switch member, a thermally responsive element heated by the current o the circuit and operable when heated a predetermined amount to eiect operation of said operating means, a movable lever mounting both said switch member and said thermally responsive and adjusting means for moving said lever to vary the tripping time of the breaker.

8. A circuit breaker comprising separable contact means, a switch member' movable to open and close said contact means, releasable operating means for actuating said switch member, a bimetal element heated by the current of the circuit and operable when heated a predetermined amount to release said operating means and effect automatic opening of said contact means, a movable ever upon which said switch member and said bimetal element are mounted, adjusting means for moving said lever to vary the tripping time of the breaker, and a temperature responsive element attached to said pivoted lever and disposed between said lever and said adjusting means for compensating said bimetal element for changes in ambient temperatures.

9. A circuit breaker comprising separable contact means, a resilient switch member movable to open and close said contact means, operating means for actuating said switch member, a bimetal element responsive to overload currents to effect operation oi said operating means and automatic opening of said contact means, a movable lever upon one side of which said switch member and said bimetal element are mounted, adjusting means for moving said lever to simultaneously varv the contact pressure and the trip-- ping time of the breaker, a temperature responsive element mounted on the other side of said lever and disposed between said lever and said adjusting means for compensating said bimetal element for changes in ambient temperature, and resilient means for maintaining said temperature responsive element in engagement with said adjusting means.

i0. la circuit breaker movable contact means, a switch member biased in opening direction and mov-able to open and close said contact means, a rotatable member having cam means thereon engaging said switch memberto hold said switch member in closed position against its bias, manual means for en gaging rotating said rotatable member in one direction to disengage said cam means from said switch member and permit opening Inovement of said switch member, and trip means operable in response to overload currents for effecting rotation of said rotatable member in the comprising relatively opposite direction to disengage said cam means from said switch member and eilect automatic opening movement of said switch member.

11. A circuit breaker comprising relatively movable contact means, a switch member movable to open and close said contact means, means biasing said switch member in opening direction, a rotatable cam member having a plurality of cam projections thereon, one or' said cam projections normally engaging said switch member to hold said switch member in closed position, said biasing means normally biasing said cam member for rotation in one direction, a releasable member releasably restraining said cam member against rotation in said one direction, trip means operable to release said releasable means to permit said biasing means to rotate said cam member in said one direction and to move said switch member to open position, and manual means engageable with said cam member for rotating said cam member in said one direction to engage the succeeding cam projection with said switch member and move said switch member to closed position.

12. A circuit breaker comprising relatively movable contact means biased open, a rotatable cam member having a plurality of cam projections spaced about the periphery thereof, one of said cam projections normally engaging said movable contact means to hold said contact means closed, said cam member being rotatable step by step in one direction to first disengage said one cam projection from said contact means and effect automatic opening oi said contact means and then engage the succeeding cam projection with said contact means to effect closing of said contact means, trip means operable to eiect rotation of said cam member one step to effect automatic opening or said contact means, and manual means operable to engage said cam member and effect rotation of said cam member another step to close said contact means.

13. A circuit breaker comprising relatively movable contact means biased open, a rotatable cam member having a plurality or cam projections spaced about the periphery thereof, one of said cam projections normally engaging said contact means to hold said contact means closed, said cam member being rotatable step by step in one direction to rst disengage said one cam projection from said contact means and effect automatic opening of said contact means and then engage the succeeding cam projection with said contact means to eirect closing of said contact means, trip means operable to eiect rotation of said cam member one step to eiect automatic opening of said contact means, and manual means operable to engage said cam member and eiect rotation of said cam member another step to close said contact means, said cam member advancing one cam projection for each automatic opening and subsequent closing operation.

14. A circuit breaker comprising relatively movable contact means, a resilient switch member movable to open and close said contact means, operating' means operable to effect automatic opening movement of said switch member, a thermally responsive element disposed in electrical engagement with said switch arm, said thermally responsive element being heated by the current of the circuit and operable when heated a predetermined amount to effect an operation of said operating means, a movable lever mounting both said switch arm and said thermally responsive element, and adjusting means for moving 9 said lever to vary the tripping time of said breaker.

15. A circuit breaker comprising stationary and movable contact means, a switch member carrying said movable contact means and biased to open position, a rotatable member having a plurality of radially extending projections thereon, one of said radial projections normally engaging said switch member to maintain said switch member closed against its bias, a latch member having a portion engaging another of said radial projections to releasably restrain said rotatable member, and a trip device operable to release said latch member and permit said biased switch member to rotate said rotatable member to disengage said one radial projection from said switch member to effect automatic opening movement of said switch member.

16. A circuit breaker comprising stationary and movable contact means, a switch member carrying said movable contact means and biased in opening direction, a cam member rotatable about a. pivot normally engaging and restraining said switch member in closed position against its bias, a releasable member normally engaging and restraining said cam member, means releasably restraining said releasable member in restraining position, manual means movable in one direction to engage and aotuate said releasable member to cause said releasable member to rotate said cam rection to cause said cam member to move said f switch member to closed position.

17. A circuit breaker comprising a switch member movable to open and close the circuit, means biasing said switch member in opening direction, a rotatable cam member having a plurality of radially extending cam portions thereon, one of said radial cam portions being normally in a position to engage and restrain said switch member in closed position, said biasing means normally biasing said cam member for rotation in one direction, a releasable member engaging another one of said radial cam portions t restrain said cam member in said restraining position, a trip device normally restraining' said releasable member and operable in response to overload currents to release said releasable member to permit said biasing means to rotate said cam member in said one direction and to move said switch member to open position, and manual means movable in one direction to engage and reset said releasable member and operable when moved in another direction to engage and advance said cam member to cause the succeeding radial cam portion to engage and move said switch member to closed position.

" GERALD J.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 2,071,848 Lindstrom Feb. 23, 1937 2,160,236 Taylor May 30, 1939 2,270,150 Taylor Jan. 13, 1942 2,340,050 Gano Jan. 25, 1944 2,454,106 Von Hoorn Nov. 16, 1948 2,467,797 Wise Apr. i9, 1949 

